The present invention relates to an ultra micro indentation testing apparatus. More particularly, the present invention relates to a novel ultra micro indentation testing apparatus, which can achieve minute hardness measurement or material surface observation for evaluating mechanical characteristics of the fine structure of a functional material, and which is useful for evaluating the functional material or setting guidelines for development of the functional material.
In the electric, electronic or communication industry, high performance and material advancement have been remarkably developed in recent years. An important problem to be solved is to measure the hardness or Young""s modulus of a surface on a crystalline grain boundary, or of a minute region in the vicinity of the tip of a crack, a thin film, an oxide film at the surface of the material, a laminated film or an ion implantation layer with high accuracy at a nanoscopic level as one of techniques for supporting the high performance and advance of the material.
A Vickers hardness tester has been conventionally used for the purpose of measuring the surface hardness of material. Moreover, there has been recently proposed a surface hardness measuring method, in which an atomic force microscope (AFM) is used as it is. However, it is difficult to achieve the accuracy at a nanoscopic level in the measurement by the above-described conventional methods.
The inventors of the present application have proposed a novel surface hardness measuring apparatus capable of highly accurate measurement at a nanoscopic level in place of the above-described conventional measuring methods (Japanese Patent No. 2725741). As shown in FIG. 22, the apparatus is a surface hardness measuring apparatus comprising a center lever (201) having a probe (202) disposed at the center thereof, a center lever stand (204) for fixing the center lever (201), a uniaxial actuator (205) for the center lever, a triaxial observing actuator (207) for changing the position of a sample, and a displacement gage (206). The probe (202) disposed in the center lever (201) is vertically pushed in the surface of a sample (203), and then minute hardness is measured by measuring a force and a penetration depth at that time. Furthermore, a tension adjusting means for adjusting an interval between lever arms (214) and (215) opposite to each other in the center lever stand (204) so as to adjust tension to be applied to a center lever is interposed between the lever arms (214) and (215) in one example of modes, as shown in FIG. 23. The tension adjusting means includes a screw means (213) which abuts against the inside of one of the lever arms at one end thereof, and spring members (216) and (217) respectively consisting of the lever arms opposite to each other in the center lever stand by forming cutouts.
The above-described invention by the inventors of this application has enabled the hardness of material to be measured at a nanoscopic level in an indentation test. However, since an indenter for carrying out the indentation test also serves as a probe for observing a surface, there has arisen a problem of an insufficient resolution at the time of the observation. In order to solve such a problem, the hardness measurement and the surface observation might be individually performed by two different testing machines. However, such means for solving the problem is not desired from the viewpoints of the difficulty of reproducing the same position of a sample in the two different testing machines, efficiency of tests or cost reduction of the testing machines.
The present invention has been accomplished in view of the above-described circumstances. Therefore, the problem to be solved by the present invention is to provide a testing apparatus equipped with both the function of measuring the hardness of the surface of material in an ultra micro region and the function of observing the surface by an AFM with high accuracy.
According to the present invention, in order to solve the above-described problem, an ultra micro indentation testing apparatus includes a lever stand provided with a center lever having a probe and an indenter disposed therein; a moving mechanism for moving the lever stand in a triaxial direction; an indentation mechanism for pushing the indenter in a sample; a displacement gage for measuring a displacement of the probe or the indenter; and an optical picture device for use in (assisting with) positioning the probe or the indenter and observing the surface of the sample. The apparatus has, in combination, a hardness measuring function based on measurement of the force and depth of the indenter pushed in the surface of the sample, an atomic force microscopic function of acquiring the shape of the surface of the sample based on a displacement of the probe or the indenter, and an optical microscopic function of observing the surface of the sample by the optical picture device.
Furthermore, according to the present invention, a hole for setting a center lever is formed at the center of the lever stand; a groove for setting the center lever is formed at the side face of the lever stand; the indenter is provided at part of the center lever; and a positioning mark is made at part of the center lever.
Moreover, according to the present invention, a plurality of probes are provided in the lever stand; a plurality of center levers are provided in the lever stand; the probe is made of silicon or a substance like silicon, which is easily machined into a sharp shape, and the indenter is made of diamond or a hard substance like diamond; and the above-described apparatus may further comprise a mechanism for remotely controlling the movement of the lever stand with the accuracy on the order of a micrometer.